This application is based on and incorporates herein by reference Japanese Patent Application No. 2002-101327 filed on Apr. 3, 2002 and Japanese Patent Application No. 2003-27578 filed on Feb. 4, 2003.
1. Field of the Invention
The present invention relates to a heat exchanger, such as an evaporator of a vehicle air conditioning system.
2. Description of Related Art
For example, Japanese Unexamined Patent Publication No. 2001-74388 discloses a heat exchanger. The disclosed heat exchanger is an evaporator of a vehicle air conditioning system and includes a plurality of tubes. The tubes are arranged in two rows, which are arranged in a flow direction of external fluid that flows outside of the evaporator. In each row of tubes, opposed upper and lower ends of each tube are directly connected to adjacent upper and lower tank arrangements, respectively, such that the tubes and the tank arrangements form a refrigerant flow passage. Partition walls are arranged in the tank arrangements. The partition walls allow the refrigerant to flow through a refrigerant flow passage section defined in one of the two rows of tubes in one direction and then flows through a refrigerant flow passage section defined in the other one of the two rows of tubes in an opposite direction opposite to the one direction. Furthermore, a plurality of throttle plates are arranged in predetermined positions in the corresponding tank arrangement to reduce a passage cross sectional area in the tank arrangement.
With the above arrangement, a refrigerant inlet side refrigerant passage section, in which a relatively large amount of liquid phase refrigerant exists near a refrigerant inlet, and a refrigerant outlet side refrigerant passage section, in which a relatively large amount of vapor phase refrigerant exists near a refrigerant outlet, are arranged in series in the flow direction of external fluid. Thus, even when the flow rate of the refrigerant is relatively small, the temperature distribution of the outlet air discharged from the evaporator becomes more uniform.
Furthermore, the throttle plates allow adjustment of distribution of the refrigerant, and the unequal distribution of the refrigerant is alleviated by the arrangement of the tubes in the two rows, which are placed one after the other in the flow direction of external fluid to provide more uniform temperature distribution of the outlet air discharged from the evaporator.
However, in order to adjust the temperature distribution of the outlet air discharged from the evaporator in a more precise manner, the number of throttle plates needs to be disadvantageously increased, resulting in an increase in the number of the components. Furthermore, the increase in the number of throttle plates results in an increase in pressure loss of the refrigerant. Also, since each tube is directly connected to the corresponding tank arrangement such that an end of the tube protrudes into an internal flow passage of the tank arrangement, the end of the tube could restrain smooth flow of refrigerant through the tank arrangement and could result in an increase in pressure loss of the refrigerant.
The present invention addresses the above disadvantage, and thus it is an objective of the present invention to provide a heat exchanger, which is capable of minimizing pressure loss of internal fluid and is also capable of improving temperature distribution of external fluid with a relatively simple structure. It is another objective of the present invention to provide a manufacturing method of such a heat exchanger.
To achieve the objectives of the present invention, there is provided a heat exchanger for exchanging heat between internal fluid inside the heat exchanger and external fluid outside the heat exchanger. The heat exchanger includes a plurality of aligned tubes and at least one header tank unit, each of which includes a plurality of fluid conduits communicated with the plurality of tubes. Each header tank unit further includes a communication hole defining means for defining a plurality of communication holes therethrough. Each communication hole communicates between a corresponding one of the plurality of tubes and a corresponding one of the plurality of fluid conduits of the header tank unit such that each tube is spaced apart from the corresponding one of the plurality of fluid conduits.
To achieve the objectives of the present invention, there is also provided a manufacturing method of a heat exchanger. According to the method, a plurality of communication holes is formed through an intermediate plate. Then, a header tank unit, which includes the intermediate plate, is assembled. Thereafter, a plurality of tubes is installed to the header tank unit. Then, the tubes are joined to the header tank unit by soldering.